1. Field of the Invention
This disclosure relates to a backlight unit, and more particularly, to a backlight unit adapted to enhance brightness and reduce manufacturing time and costs, as well as a liquid crystal display device having the same.
2. Discussion of the Related Art
Cathode ray tubes (CRTs), which are widely used display devices, are mainly used as TVs or monitors for measuring apparatuses or information terminals. However, the heavy weight and large size of CRTs have been a major hindrance to the manufacturing of small, light electronic products.
To address this matter, LCD devices are gradually being used in a wide range of applications due to their advantages such as lightness, thinness, and low power consumption. Accordingly, LCD devices are being manufactured to have even larger screens, be thinner, and consume less power. Such LCD devices display images by controlling the amount of light transmitted through liquid crystal.
LCD devices are not self-illuminating display devices, unlike CRTs. As such, an LCD device includes a backlight unit provided on the rear surface of an LCD panel. The backlight unit includes a separated light source providing the light necessary to display an image. Actually, the backlight unit employs a plasma type light source such as a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electrode fluorescent lamp (EEFL), an external and internal electrode fluorescent lamp (EIFL), or others. Alternatively, the backlight unit uses a white light emission diode (LED) as a light source. Particularly, the white LED configured to emit white light is widely used in the backlight unit because of its features of long lifespan, low power consumption, small size, durability, and others.
FIG. 1 is a cross-sectional view showing a backlight unit according to the related art.
As shown in FIG. 1, a backlight unit of the related art includes a printed circuit board (PCB) 51 which is disposed on an edge of the inner side of a bottom cover 90 and loaded with a plurality of LEDs 50. The backlight unit further includes a reflection sheet 80, a light guide plate 40, and optical sheets 30 which are sequentially received into the bottom cover 90. The bottom cover 90 is combined with a support main 15 in order to secure the reflection sheet 80, the light guide plate 40, and the optical sheets 30. The PCB 51 is attached onto the inner surface of a side wall of the bottom cover 90 by means of a first adhesive tape 60.
Furthermore, the backlight unit includes a light reflection housing 81 disposed on a rear surface region of the support main 15 which is overlapped with the light guide plate 40. The light reflection housing 81 is attached onto the rear surface region of the support main 15 by a second adhesive tape 61. The light reflection housing 81 minimizes light leakage caused by light which is emitted toward the support main 15, when the LEDs 50 emits lights.
Such a configuration of the related art backlight unit causes gaps between the light reflection housing 81 and the light guide plate 40 as well as between the light reflection housing 81 and the optical sheets 30, by assembly tolerances. These gaps make it difficult to improve brightness deterioration in the incident portion of the light guide plate 40 which receives light from the LEDs 50, even though the related art backlight unit includes the light reflection housing 81. Moreover, the light reflection housing 81 and second adhesive tape 61 corresponding to additional parts of the related art backlight unit increase the manufacturing time and costs.